Survey of organochlorine pesticides in horticultural soils and there grown Cucurbitaceae

Summary

Organochlorine pesticides (OCP) are still found in food and feed crops although they were applied about 40 years ago. There is a considerable knowledge gap concerning the extent of soil and crop contamination by OCP. We performed two surveys in 2002 and 2005 to assess the loads of OCP in 41 Swiss horticultural fields under organic and conventional production and corresponding Cucurbitaceae fruits (cucumbers, zucchini, and pumpkin), whereas these fields stay for intensive agricultural production in Europe. In addition, soil organic carbon, texture, and pH were measured also. OCP were detected in 27 out of 41 fields (65.9%). The farming practice had no influence on the contamination or level of OCP in soil. The sum of OCP-loads per field ranged from <0.01 to 1.3 mg kg−1 dry soil and pentachloroaniline (PCA, 2.1 mg kg−1), p,p′-DDT (0.5 mg kg−1), and p,p′-DDE and dieldrin (0.4 mg kg−1) were the most detected pesticides over all investigated soils. PCA (up to 0.02 mg kg−1), dieldrin (up to 0.04 mg kg−1), α-chlordane and cis-heptachloroepoxide (<0.01 mg kg−1) were detected in five cucumber samples out of 41 Cucurbitaceae samples. Statistical analysis revealed no significant influence of the measured soil properties on the OCP-load of soils and cucumbers, although there is evidence that the bioavailability of OCP in soils to Cucurbitaceae plants was influenced by the sorption of the compounds to soil organic matter and by the polarity of the pesticide molecules. It is suggested, that OCP contamination is widespread in all European regions with intensive plant production and associated pesticide use, and deserves more attention with respect to save food production.